This invention relates to a liquid treatment apparatus comprising semi-permeable hollow fibers which have continuous hollow chambers (hereinafter referred to merely as "hollow fibers") in which exchange or transfer of substances is performed between a liquid flowing inside the hollow fibers (hereinafter referred to as "inside liquid") and liquid flowing outside the hollow fibers (hereinafter referred to as "outside liquid") through the semi-permeable membrane of the hollow fibers. More particularly, this invention relates to a liquid treatment apparatus which is especially effective for shortening the treatment time by increasing the flow rate of the outside liquid. Further, when this apparatus is used for passing blood through the interior of the fibers in the manner such as that employed in the conventional coil-type artificial kidney dialysis apparatus, including a semi-permeable tube wound in a coil-like shape, an excellent blood-cleaning effect can be attained.
There is known in the art a liquid treatment apparatus comprising a vast plurality of semi-permeable hollow fibers (for example about ten thousand hollow fibers) arranged and gathered in parallel relationship to one another in a cylindrical bundle, a cylindrical vessel having an introduction opening and a discharge opening for an outside liquid, said bundle of hollow fibers being arranged in a straight line within said vessel without disturbing the parallel relationship among the fibers, supporting and partitioning members for the hollow fibers, which members are formed by filling in a liquid tight manner only at both end portions of the hollow fibers an adhesive in the spaces among the hollow fibers and between the hollow fibers and the walls of said vessels to thereby prevent the inside liquid from mingling directly with the outside liquid without passing through the semi-permeable membrane of the hollow fibers, and an inlet and an outlet for the inside liquid, which communicate with the terminal ends of the fiber bundle, respectively.
In a conventional dialysis apparatus of this type, however, because a vast plurality of hollow fibers are gathered in a relatively high density, it is almost impossible for the outside liquid to pass uniformly all of the clearances between every two adjacent fibers, and in some parts, the outside liquid does not flow sufficiently but is stagnant. Accordingly, some parts of surfaces of the membrane are not sufficiently utilized for dialysis and the merit attained by use of hollow fibers, namely the merit that the effective surface area of the membrane per unit vessel volume is large, is not fully realized. In fact, no commercially sufficient result has been obtainable when the exchange or transfer of substances is conducted through the semi-permeable membrane of the conventional apparatus.
Even when it is intended to provide sufficient clearances among hollow fibers so as to eliminate the foregoing defect, there is brought about another defect in that the capacity of the vessel must inevitably be increased, and furthermore, it is technically difficult to dispose equidistantly fine hollow fibers with sufficient clearance between adjacent fibers. Especially, when an attempt is made to use this apparatus as an artificial kidney by passing blood in the interior hollow portions of the fibers, the size of the blood inlet and outlet formed at the terminal ends of the fiber bundle should invitably be increased in proportion to the increased volume of the vessel and it often happens that blood taken out of the body of patient exceeds the critical volume of the vessel during the blood-cleaning treatment and therefore, difficulties are involved in using this apparatus as an artificial kidney.
Moreover, in the above-mentioned conventional apparatus, since a vast plurality of hollow fibers are gathered relatively closely and packed tightly in the cylindrical vessel, it is difficult to increase the flow rate of the outside liquid, and if the flow rate of the outside liquid is increased by force, the fluid flows only through portions where it can flow with ease. Accordingly, it has been impossible to shorten the treatment time by this conventional apparatus.
We made various research efforts and experiments and have succeeded in developing an apparatus in which the capacity of transfer of substances through a semi-permeable membrane of hollow fibers can be greatly increased without reducing the merit of the use of hollow fibers, namely the merit that the apparatus capacity can be reduced.